Cicadas

Cicada on a tree

Cicadas are well known for the shrill, non-stop call of the males but I wonder how many people have actually seen one? Although you can easily hear them it is hard to track down the source of the noise. Some sources say that there are over 3,000 species of these noisy critters worldwide. South Africa has around 150 species.

What do Cicadas look like?

Cicadas are normally green or brown in colour and around 4 cm in length. They feed off the sap from plants. They have five eyes! These consist of two large ones and three small ones in between. Only the males make the mating call, and they do this by vibrating their tymbals which are essentially vibrating surfaces. The sound is amplified by membranes within the cicada’s body. The females hear the noise through ears that are located on her abdomen. Interestingly the abdomen of the male is more or less hollow and acts as a resonating chamber.

Imagine spending 17 years underground

The female Cicada lays her eggs in slits which she has cut into the bark of a tree. Once the nymphs emerge from the eggs they drop to the ground and burrow into the soil. They tunnel down 2 metres or more. While in the nymph phase of their lives the cicadas feed off sap from the roots of trees. I am not sure how long the South African cicadas stay in their nymph form but there is a well-known species in north America that spends between 13 to 17 years before they emerge. When the nymph is ready to take on its adult form it emerges from the ground and climbs up the tree trunk to a height of 30 cm or so. At this point its nymphal skin splits and allows the adult to emerge.

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